That history is pretty unsatisfying when it first quotes Holmes, presumably a century or so after the constitution was ratified. So next I looked at http://en.wikipedia.org/wiki/Sovereign_immunity_in_the_Unite... and it cites a case from 1983. This makes me at least wonder at the idea it derives directly from English law at the founding of the U.S.; "you can't sue the King" does not obviously transfer right over in the atmosphere of the time.

ianal or historian.